Hard-coded error_reporting breaks API on PHP 8.1

Nobody has claimed this yet.

Wondering why `error_reporting` is hardcoded in `api.php`?

```php
error_reporting(E_ERROR|E_CORE_ERROR|E_ALL|E_COMPILE_ERROR); //
ini_set('display_errors', 'On');
```

I spent quite some time wondering why my settings in `php.ini` weren't working to finally figure out they were overwritten.

Trouble is, your `composer.json` does not fix a PHP version, e.g. `7.4` and so we end up with dependencies that require `8.1` in some situations (Think docker multi-stage builds…).

With 8.1 and the level of `error_reporting` hard-coded in `api.php`, the result on an API call is:

```


Deprecated: Implicit conversion from float 0.1 to int loses precision in /var/www/html/quickstatements/public_html/quickstatements.php on line 1096

{"status":"OK","command":{"action":"create","type":"item","data":{"claims":[{"mainsnak":{"snaktype":"value","property":"P1","datavalue":{"type":"wikibase-entityid","value":{"entity-type":"item","id":"Q17"}}},"type":"statement","rank":"normal"},{"mainsnak":{"snaktype":"value","property":"P18","datavalue":{"type":"string","value":"I made a second attempt of a QS"}},"type":"statement","rank":"normal"}]},"meta":{"message":"","status":"RUN","id":0},"summary":"#temporary_batch_1660059860160","status":"done","run":{"action":"wbeditentity","new":"item","data":"{\"claims\":[{\"mainsnak\":{\"snaktype\":\"value\",\"property\":\"P1\",\"datavalue\":{\"type\":\"wikibase-entityid\",\"value\":{\"entity-type\":\"item\",\"id\":\"Q17\"}}},\"type\":\"statement\",\"rank\":\"normal\"},{\"mainsnak\":{\"snaktype\":\"value\",\"property\":\"P18\",\"datavalue\":{\"type\":\"string\",\"value\":\"I made a second attempt of a QS\"}},\"type\":\"statement\",\"rank\":\"normal\"}]}","summary":"#quickstatements; #temporary_batch_1660059860160","bot":1,"token":"************************+\\","format":"json"},"item":"Q1162"},"last_item":"Q1162"}
```

Start with api.php and composer.json, then reproduce an API call under PHP 8.1 while checking the error reported from public_html/quickstatements.php line 1096. Confirm the resulting API response is valid JSON and that the configured PHP error-reporting behavior is not unexpectedly overwritten.

Written by the indexing model from the issue text.